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Find the area of a triangle …

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Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm.

    • Posted by Janvi Shevate 5 years, 2 months ago

    CBSE > Class 09 > Mathematics
    • 3 answers

    Rakhi Vasodiya11 5 years, 2 months ago

    √(21-18)(21-10)(21-14) √ 3 × 11 × 7 √231 cm sq.

    1Thank You

    Rakhi Vasodiya11 5 years, 2 months ago

    Perimeter = sum of all sides of triangle i.e. 42 = 18+10+c 42 = 28+c 42-28=c 14=c Then, semi - perimeter = a+b+c/2 = 18+10+14/2 = 42/2 = 21 cm. Now, you can easily find area using heron's formula

    1Thank You

    Yogita Ingle 5 years, 2 months ago

    Given,
    Side a=18cm
    Side b=10cm
    Perimeter=42cm=a+b+c
    :. Putting value
    42=18+10+c
    42=28+c
    42-28=c
    14=c
    Now,
    S=(a+b+c)/2
    :. Putting value
    S=42/2
    S=21
    Now according to Heron's formula-
    Area of a triangle
    =√{s(s-a)(s-b)(s-c)}
    :. Putting value
    =√{21(21-18)(21-10)(21-14)}
    =√{21(3)(11)(7)}
    =√4851
    =21√11cm²

    1Thank You

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